金字塔沙丘流场的三维数值模拟

摘要/Abstract

摘要： 对位于敦煌莫高窟顶部鸣沙山东麓的金字塔沙丘流场形态进行数值模拟,分析了多风向条件下沙丘的压力场和速度场变化规律。使用地面立体摄影技术获取沙丘的控制点坐标,建立了与实地沙丘等比例的三维模型,以解决二维建模不能表达3组主风向差异的问题。使用计算流体动力学（CFD）方法,采用非结构网格划分技术以适应沙丘的高度不规则地形,通过剪切压力传输模型（SST）分析计算并与以往风洞试验和数值模拟结果进行对比。模型很好地预测了沙丘底部停滞区、坡上加速区、背风坡回流区以及沙丘表面压力和风速分布等流场信息,反映了多风向条件下沙丘形态与气流的交互作用。流场中速度场的分布与压力分布直接相关。

关键词: 金字塔沙丘, 流场, 三维数值模拟, 地面立体摄影

Abstract: In this paper, the airflow field of a pyramid dune, which is located at the eastern edge of the Mingsha Mountain atop the famous Mogao Grottoes, was simulated by numerical simulation. Changes of pressure field and velocity field over the dune surface under multidirectional wind regime were analyzed. A 3-dimensional numerical model in equal proportion to the real dune was built with the help of ground stereo photogrammetry. The variances of three prevailing wind directions that cannot be expressed by previous 2-dimension models were obtained. Unstructured grid method was used to adjust to the highly irregular terrain of the pyramid dune. In our computational fluid dynamics simulations, the so-called shear-stress transport-model was applied and the results were compared with previous wind tunnel measurement and numerical simulation works. It indicates that this 3-dimensional model can successfully predict the information of the whole airflow field, including the stagnation zone at the toe, the accelerating region up the stoss slope, the recirculation region in the lee, the wind velocity and pressure distribution patterns and so on. Besides, the flow-dune form interaction is expressed more comprehensively. Velocity pattern is directly related to the pressure distribution in the flow field.

Key words: pyramid dune, airflow field, 3-dimensional numerical simulation, ground stereo photogrammetry

中图分类号:

X169

柳本立;张伟民;彭飞;谭立海;. 金字塔沙丘流场的三维数值模拟[J]. 中国沙漠, 2011, 31(2): 386-392.

LIU Ben-li;ZHANG Wei-min;PENG Fei;TAN Li-hai;. Numerical Simulation of Airflow Field over a Pyramid Dune[J]. JOURNAL OF DESERT RESEARCH, 2011, 31(2): 386-392.

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